Conventionally, as one function of a storage apparatus, there exists a data management function for migrating files stored by a client/host in a logical volume to another storage apparatus such as an archive apparatus on the basis of a prescribed policy determined beforehand (a conditional equation based on a reference frequency or the like, for example) (refer to PTL1).
A storage apparatus that is equipped with a data management function of this type stores metadata (hereinafter referred to as a stub file), which is obtained by recording address information of a file migration destination in a source storage location, in order to hide the fact that the file storage location has changed from the client/host. Further, if there is a read request for a file that has been migrated to another storage apparatus, the storage apparatus acts as if the file were in the original storage location by acquiring the corresponding file from another storage apparatus of the migration destination on the basis of the address information contained in the stub file and transferring the acquired file to the read request source. This behavior is known as recall processing. Note that, as a well-known example of a method for efficiently controlling backup data (snapshots) of a plurality of generations in an HSM (Hierarchical Storage Management) system, there exists PTL2.
Citation List
Patent Literature
[PTL1] U.S. Patent Publication No. 7225211
[PTL2] Japanese Unexamined Patent Publication No. 2008-40699